The present invention relates generally to optical systems and elements and more specifically to polarization and modulation of coherent light sources using electrically responsive materials. Devices for performing these functions have been known in the prior art as electro-optic modulators. Generally, these devices operate by directing a light beam to be modulated onto a modulator material and applying an electrical field to the modulator material to cause a change of refraction of the material thereby causing a phase change to be induced between the two polarization components of the incident light beam. Depending upon the polarization of the incident beam, the resultant light beam may be either polarization, phase, or frequency modulated by the modulator material. If the beam is polarly modulated, it may be followed by a polarization analyzer which will result in a beam which is only intensity modulated.
In order to efficiently modulate the input beam, a phase shift of approximately 180.degree. must be induced by the modulator. For the prior devices this requires voltage levels of a few thousand volts for most materials. In addition, modulation at high frequencies requires a great deal of power because of the high voltages. Thus the conventional electro-optic modulator requires inconveniently high voltages and, at high frequencies, high powers.
Although other types of modulators, such as mechanical and acousto-optic modulators have been devised, they have been found to be incapable of modulating at frequencies as high as the electro-optical modulators.